**** being politically correct, be contextually correct.

miimii f' I? Jack
Dear activists trying to
eliminate the word "Retarded". Retarded is
not slang for somebody who is mentally or
physically handicapped or has a learning
disability. Retarded means slow or delayed.
To put it contextually, retarded means
possessing a slow thought process or "dim
witted". So to an extent, yes, retarded IS
interchangeable with Stupid. Ban the misuse
of the word labeling of People with
disabilities, not the word in other situations.
Get that through your retarded
misunderstanding heads. End rant.

I can't walk since the day I was born, buddy, wheelchair for life. And there's nothing I hate more than people calling me "special", "handicapped" or "impeded". I rather they just call me a cripple, or Bob.
you either are an ass and call me bad ****, or have the balls to treat me like any other person, but please don't patronize me, is insulting.

To elaborate:
"Free speech" is the inherent right of people to express their opinions, be they religious, political, or anything else. Insulting people does not fall under free speech, which is why you can be arrested and/or fined for slander. Using words does not fall under free speech either, which is why you can be arrested and/or fined if you say, begin cursing in an elementary school.
tl;dr-- Anon don't know ****.

Technically speaking, insulting people does fall under free speech, so long as I have no proof or knowledge that the claim I am making is not true. For example, having never met you, if I were to claim you are retarded (meaning mentally challenged, not dim witted, although either works), you couldn't sue me for slander (spoken only) or libel (written only), because I have no knowledge that the statement I made is not true. However, if we were great friends and I was aware you had no mental deficiencies, such as if I knew you were valedictorian, and I called you a retard (again in either meaning), you could subsequently sue me, as I knew my statement was false.

In addition, it is generally assumed, and nearly always ruled, that for a statement to be libelous or slanderous, it must be harmful to your current economic, political, or social standing, as well as being known, by the person making the claim, to be untrue.

The reason you can be arrested for cursing in an elementary school is, I believe, more to do with disturbing the peace and disrupting education, as speech is the first enumerated right following the separation of religion from the state, than anything else. This would also explain why it was recently ruled that you are within your Constitutional rights to 'flip off' both on and off duty police officers, regardless of knowledge of their job. Generally, 'flipping someone off' is considered as crude as cursing, yet is protected as free speech when it does not disrupt the God given right to education (Read: I only say God given due to it generally being called that, not due to personal beliefs), or impede or obstruct official duties.

TL;DR Libel/Slander: must hurt target's standing and be known to be untrue
Cursing in elementary school: context over content

Actually it kind of is. I know I'm falling on the red thumb side of this argument, but whatever. Remember that offense can never be given, it can only be taken. A word or phrase or statement that one person finds offensive might not be offensive to somebody else. So to ban offensive or insulting words would be such an abstract endeavor that it would only lead to confusion and gross double-standards.

Now, the act of intentionally offending, belittling, or hurting someone through the use of language is called "harassment", and is already dealt with in most legal systems.